81MANGANESE (IV) OXIDE: The chemical compound MnO2, commonly called manganese dioxide.
This blackish or brown solid occurs naturally as the mineral pyrolusite, which is the main ore of
manganese. It is also present in manganese nodules. The principal use for MnO2 is for dry-cell
batteries, such as the alkaline battery and the zinc-carbon battery. In 1976 this application
accounted for 500,000 tons of pyrolusite. MnO2 is also used for production of MnO4–. It is used
extensively as an oxidizing agent in organic synthesis, for example, for the oxidation of allylic
alcohols.
MAXIMUM CONTAMINANT LEVEL (MCL): The maximum concentration of a chemical that is
allowed in public drinking water systems.
MAXIMUM CONTAMINANT LEVEL GOAL (MCLG): The maximum level at which a contaminant
can exist in drinking water without having an adverse effect on human health.
NEPHELOMETRIC TURBIDITY UNIT (NTU): The unit used to describe turbidity. Nephelometric
refers to the way the instrument, a nephelometer, measures how much light is scattered by
suspended particles in the water. The greater the scattering, the higher the turbidity. Therefore, low
NTU values indicate high water clarity, while high NTU values indicate low water clarity.
PERMISSIBLE EXPOSURE LIMIT (PEL or OSHA PEL): A legal limit in the United States for
exposure of an employee to a substance or physical agent. For substances it is usually expressed
in parts per million (ppm), or sometimes in milligrams per cubic meter (mg/m^3 ). Units of measure
for physical agents such as noise are specific to the agent. Permissible Exposure Limits are
established by the Occupational Safety and Health Administration (OSHA).
POWDERED ACTIVATED CARDON TREATMENT (PACT): A wastewater technology in which
powdered activated carbon is added to an anaerobic or aerobic treatment system. The carbon in
the biological treatment process acts as a "buffer" against the effects of toxic organics in the
wastewater.
PPM: Abbreviation for parts per million.
QUICKLIME: A calcium oxide material produced by calcining limestone to liberate carbon dioxide,
also called “calcined lime” or “pebble lime”, commonly used for pH adjustment. Chemical formula
is CaO.
RECOMMENDED EXPOSURE LIMIT (REL): An occupational exposure limit that has been
recommended by the U.S. National Institute for Occupational Safety and Health to OSHA for
adoption as a Permissible Exposure Limit. The REL is a level that NIOSH believes would be
protective of worker safety and health over a working lifetime if used in combination with
engineering and work practice controls, exposure and medical monitoring, posting and labeling of
hazards, worker training and personal protective equipment. No REL has ever been adopted by
OSHA, but they have been used as guides by some industry and advocacy organizations.
SCADA: A remote method of monitoring pumps and equipment. 130 degrees F is the maximum
temperature that transmitting equipment is able to with stand. If the level controller may be set with
too close a tolerance 45 could be the cause of a control system that is frequently turning a pump
on and off.